We present a system level architecture for supporting mobility in an ATM-based wireless personal communication network (PCN). The proposed architecture uses a networking scheme based on intelligent, multicast-based trees with distributed mobility management and predictive resource allocation at the base stations. The addressed functionalities include connection admission, location management and tracking and handoff procedure with QoS support. The associated protocols for implementing these functions are outlined and the architecture is compared vis-a-vis currently existing proposals in the literature. In doing so we discuss key design issues, and speculate on future directions in the development of broadband wireless packet communications systems